The last index in your [2:4] slice is not inclusive. This means slicing your string like that will result in '06'.

If you want '068', you need to take the [2:5] slice.

Then, converting to a float using float('068') should give you 68.0.

I don't get why slicing your string using the [2:5] slice would return '068;'. I've tried it in my interpreter and it really only returns '068'.

Are you sure that you are using the right slices?